Publications by authors named "M G Gitau"

22 Publications

Strain-Specific Biostimulant Effects of and Green Microalgae on .

Plants (Basel) 2021 May 25;10(6). Epub 2021 May 25.

Institute of Plant Biology, Biological Research Center, 6726 Szeged, Hungary.

Microalgae have been identified to produce a plethora of bioactive compounds exerting growth stimulating effects on plants. The objective of this study was to investigate the plant-growth-promoting effects of three selected strains of eukaryotic green microalgae. The biostimulatory effects of two species (MACC-360 and MACC-38) and a strain (cc124) were investigated in a model plant grown under controlled greenhouse conditions. The physiological responses of the A17 ecotype to algal biomass addition were characterized thoroughly. The plants were cultivated in pots containing a mixture of vermiculite and soil (1:3) layered with clay at the bottom. The application of live algae cells using the soil drench method significantly increased the plants' shoot length, leaf size, fresh weight, number of flowers and pigment content. For most of the parameters analyzed, the effects of treatment proved to be specific for the applied algae strains. Overall, application led to more robust plants with increased fresh biomass, bigger leaves and more flowers/pods compared to the control and -treated samples receiving identical total nutrients.
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http://dx.doi.org/10.3390/plants10061060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8227499PMC
May 2021

nab-Paclitaxel and cisplatin followed by cisplatin and radiation (Arm 1) and nab-paclitaxel followed by cetuximab and radiation (Arm 2) for locally advanced head and neck squamous-cell carcinoma: a multicenter, non-randomized phase 2 trial.

Med Oncol 2021 Mar 8;38(4):35. Epub 2021 Mar 8.

Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, USA.

In locally advanced head and neck squamous-cell carcinoma (LA-HNSCC), clinical complete response (cCR) at the primary site, assessed by clinical examination, after induction chemotherapy predicts for a low relapse risk after subsequent chemoradiotherapy. Prior studies showed a cCR rate of 77% with induction nanoparticle albumin-bound (nab)-paclitaxel given with cisplatin and 5-fluorouracil (APF). The primary aims of this non-randomized phase 2 trial were to determine the cCR rate after induction nab-paclitaxel and cisplatin (Arm 1) and after nab-paclitaxel monotherapy (Arm 2). Eligibility required LA-HNSCC, T2-T4 stage classification, and suitable (Arm 1) or unsuitable (Arm 2) candidates for cisplatin. Arm 1 patients received nab-paclitaxel and cisplatin, then cisplatin with radiation. Arm 2 patients received nab-paclitaxel, then cetuximab with radiation. The primary endpoint was cCR after two cycles of induction chemotherapy. Each arm enrolled forty patients. cCR at the primary site occurred in 28 patients (70%) after nab-paclitaxel and cisplatin and in 8 patients (20%) after nab-paclitaxel monotherapy. The overall clinical response rate was 98% after nab-paclitaxel and cisplatin and 90% after nab-paclitaxel monotherapy. In subset analyses, cCR rates by T stage classifications (T2, T3, T4) were 54, 86, and 69% after nab-paclitaxel and cisplatin, and 14, 11, and 26% after nab-paclitaxel. cCR rates by human papillomavirus status (p16 positive oropharynx vs other) were 72 and 64% after nab-paclitaxel and cisplatin and 35 and 9% after nab-paclitaxel. The cCR rate after nab-paclitaxel and cisplatin was similar to APF; however, the cCR rate after nab-paclitaxel monotherapy was lower. The trial was registered at ClinicalTrials.gov NCT02573493 on October 9, 2015.
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http://dx.doi.org/10.1007/s12032-021-01479-wDOI Listing
March 2021

Nanoparticle albumin-bound paclitaxel with cetuximab and carboplatin as first-line therapy for recurrent or metastatic head and neck cancer: A single-arm, multicenter, phase 2 trial.

Oral Oncol 2021 04 3;115:105173. Epub 2021 Feb 3.

Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO, United States; Division of Medical Oncology, Washington University School of Medicine, St. Louis, MO, United States.

Objectives: Macropinocytosis promotes internalization of albumin into cells to serve as a nutrient supply and is constitutively driven by signaling pathways frequently hyperactivated in head and neck squamous-cell carcinoma (HNSCC). In this way, drugs bound to albumin may selectively target HNSCC. nab-paclitaxel is a nanoparticle albumin-bound formulation of paclitaxel that improves drug delivery into tumor compared to paclitaxel. The primary aim of this single-arm, multicenter, phase 2 trial was to determine if nab-paclitaxel, cetuximab, and carboplatin (CACTUX regimen) would result in longer progression-free survival (PFS) than the historical regimen (EXTREME: 5-fluorouracil, cetuximab, and a platinum).

Materials And Methods: Patients with untreated recurrent or metastatic HNSCC received six, three-week cycles of nab-paclitaxel, cetuximab, and carboplatin, followed by maintenance nab-paclitaxel and cetuximab until progression. We hypothesized the median PFS with CACTUX would be 35% longer than with EXTREME (corresponding to 7.6 vs 5.6 months; power 0.80, α = 0.05, one-sided test, n = 70). Secondary outcomes included objective response rate (ORR) and overall survival (OS).

Results: Seventy-four patients enrolled into the trial; seventy were evaluable. The median PFS was 6.1 months (95% CI, 4.1-7.4). The ORR was 60%. Median follow-up was 18 months (IQR: 4.7-23). The median OS was 17.8 months (95% CI, 8.5-21.7) for all patients, and 19.8 months (95% CI, 10.9-22.0) for human papillomavirus (HPV)-related oropharynx SCC and 14.0 months (95% CI, 4.6-23.3) for HPV-unrelated HNSCC.

Conclusion: Among patients with recurrent or metastatic HNSCC, CACTUX did not result in a longer PFS than historical EXTREME. However, CACTUX did result in a more favorable ORR and OS.
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http://dx.doi.org/10.1016/j.oraloncology.2020.105173DOI Listing
April 2021

Application of the theory of planned behavior to predict smoking intentions: cross-cultural comparison of Kenyan and American young adults.

Health Educ Res 2021 03;36(1):140-150

Center for Violence Prevention, University of Texas Medical Branch, Galveston, TX 77555, USA.

Despite well-established research on the applications of the theory of planned behavior (TPB) in the American culture, TPB has not been fully tested in the Kenyan culture. This study compared the applications of TPB in predicting smoking intentions (i.e., future and weekend smoking intentions) of Kenyan and American young adults. Data were collected from 252 Kenyans and 227 Americans. The Kenyan participants consisted of 41.7% females with a mean age of 25 years (SD = 4.81). The American participants (49.3% females) had an average age of 19 years (SD = 1.30). Multi-group path analysis was performed to test the equivalence of a TPB-based mediation model in Kenyans and Americans. Significant differences of TPB application were detected. In the American model, smoking consequence beliefs were indirectly associated with smoking intentions through attitudes whereas neither direct nor indirect effects of smoking consequence beliefs were detected in the Kenyan model. Instead, normative beliefs indirectly associated with future and weekend smoking intentions through attitudes and subjective norms in the Kenyan model. Despite some overlapping paths, there were cultural variations on specific associations among TPB constructs between Kenyans and Americans. Cultural adaptations may be needed when applying TPB in the Kenyan cultural context.
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http://dx.doi.org/10.1093/her/cyaa041DOI Listing
March 2021

Development of phosphorus sorption capacity-based environmental indices for tile-drained systems.

J Environ Qual 2020 Mar 9;49(2):378-391. Epub 2020 Mar 9.

Dep. of Agronomy, Purdue Univ., 915 W State St., West Lafayette, IN, 47907, USA.

The persistent environmental relevance of phosphorus (P) and P sorption capacity (PSC) on P loss to surface waters has led to proposals for its inclusion in soil fertility and environmental management programs. As fertility and environmental management decisions are made on a routine basis, the use of laborious P sorption isotherms to quantify PSC is not feasible. Alternatively, pedotransfer functions (pedoTFs) estimate PSC from routinely assessed soil chemical properties. Our objective was to examine the possibility of developing a suitable pedoTF for estimating PSC and to evaluate subsequent PSC-based indices (P saturation ratio [PSR] and soil P storage capacity [SPSC]) using data from an in-field laboratory where tile drain effluent is monitored daily. Phosphorus sorption capacity was well predicted by a pedoTF derived from soil aluminum and organic matter (R² = .60). Segmented-line relationships between PSR and soluble P were observed in both desorption assays (R² = .69) and drainflows (R² = .66) with apparent PSR thresholds in close agreement at 0.21 and 0.24, respectively. Negative SPSC values exhibited linear relationships with increasing soluble P concentrations in both desorption assays and drainflows (R² = .52 and R  = .53 respectively), whereas positive SPSC values were associated with low SP concentrations. Therefore, PSC-based indices determined using pedoTFs could estimate the potential for subsurface soluble P losses. Also, we determined that both index thresholds coincided with the critical soil-test P level for agronomic P sufficiency (22 mg kg Mehlich-3 P) suggesting that the agronomic threshold could serve as an environmental P threshold.
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http://dx.doi.org/10.1002/jeq2.20044DOI Listing
March 2020